WO2021134303A1 - Procédé de transformation, codeur, décodeur et support de stockage - Google Patents

Procédé de transformation, codeur, décodeur et support de stockage Download PDF

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Publication number
WO2021134303A1
WO2021134303A1 PCT/CN2019/130127 CN2019130127W WO2021134303A1 WO 2021134303 A1 WO2021134303 A1 WO 2021134303A1 CN 2019130127 W CN2019130127 W CN 2019130127W WO 2021134303 A1 WO2021134303 A1 WO 2021134303A1
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lfnst
mip
scanning order
current block
value
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PCT/CN2019/130127
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English (en)
Chinese (zh)
Inventor
霍俊彦
李新伟
乔文涵
马彦卓
万帅
杨付正
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Oppo广东移动通信有限公司
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Priority to CN201980103082.3A priority Critical patent/CN114830659A/zh
Priority to EP19958126.5A priority patent/EP4109898A4/fr
Priority to PCT/CN2019/130127 priority patent/WO2021134303A1/fr
Publication of WO2021134303A1 publication Critical patent/WO2021134303A1/fr
Priority to US17/807,639 priority patent/US20220329809A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
    • H04N19/157—Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter
    • H04N19/159—Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/12—Selection from among a plurality of transforms or standards, e.g. selection between discrete cosine transform [DCT] and sub-band transform or selection between H.263 and H.264
    • H04N19/122—Selection of transform size, e.g. 8x8 or 2x4x8 DCT; Selection of sub-band transforms of varying structure or type
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/129—Scanning of coding units, e.g. zig-zag scan of transform coefficients or flexible macroblock ordering [FMO]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
    • H04N19/176—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a block, e.g. a macroblock
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/593—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving spatial prediction techniques
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/85—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using pre-processing or post-processing specially adapted for video compression
    • H04N19/88—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using pre-processing or post-processing specially adapted for video compression involving rearrangement of data among different coding units, e.g. shuffling, interleaving, scrambling or permutation of pixel data or permutation of transform coefficient data among different blocks

Definitions

  • the embodiments of the present application relate to the field of image processing technologies, and in particular, to a transformation method, an encoder, a decoder, and a storage medium.
  • VVC High Efficiency Video Coding
  • VTM VVC Test Model
  • the simplified secondary transform (Reduced Second Transform, RST) technology has been accepted, and the name has been changed to Low-Frequency Non-Separable Transform (LFNST) technology. Since the selection of the scan order in the LFNST technology is based on the intra-frame prediction mode, but for the non-traditional intra-frame prediction mode, the lack of variability when performing LFNST transformation reduces the coding efficiency.
  • RST Reduced Second Transform
  • LFNST Low-Frequency Non-Separable Transform
  • the embodiments of the present application provide a transformation method, an encoder, a decoder, and a storage medium, which can improve the applicability of the LFNST technology to non-traditional intra prediction modes, make the selection of the scanning order more flexible, and thus can improve coding efficiency.
  • an embodiment of the present application provides a transformation method, which is applied to an encoder, and the method includes:
  • the first transform is a transform different from LFNST
  • the LFNST coefficient scanning order includes a horizontal scanning order and a vertical scanning order.
  • the embodiments of the present application provide an inverse transform method, which is applied to a decoder, and the method includes:
  • the prediction mode parameter indicates that the current block uses MIP to determine the intra-frame prediction value, parse the code stream to determine the MIP parameter;
  • the LFNST output coefficient matrix is used to construct a first coefficient matrix; wherein the LFNST coefficient scanning order includes a vertical scanning order and a horizontal scanning order.
  • an encoder which includes a first determination unit, a first calculation unit, a first transformation unit, and a first construction unit;
  • a first determining unit configured to determine a prediction mode parameter of the current block; and when the prediction mode parameter indicates that the current block uses MIP to determine an intra prediction value, determine the MIP parameter;
  • the first calculation unit is configured to determine the intra-frame prediction value of the current block according to the MIP parameter, and calculate the prediction difference between the current block and the intra-frame prediction value;
  • a first transformation unit configured to perform a first transformation on the prediction difference to obtain a first coefficient matrix
  • the first determining unit is further configured to determine the scanning order of LFNST coefficients used by the current block according to the MIP parameters when the current block uses LFNST;
  • a first construction unit configured to use the first coefficient matrix to construct an input coefficient matrix of the LFNST according to the scan order of the LFNST coefficients
  • the first transformation unit is further configured to perform LFNST processing on the input coefficient matrix to obtain the transformation coefficient matrix of the current block; wherein, the first transformation is a transformation different from LFNST, and the LFNST coefficient scanning order includes Horizontal scanning order and vertical scanning order.
  • an encoder which includes a first memory and a first processor; wherein,
  • the first memory is used to store a computer program that can run on the first processor
  • the first processor is configured to execute the method described in the first aspect when the computer program is running.
  • an embodiment of the present application provides a decoder, which includes a parsing unit, a second transformation unit, a second determination unit, and a second construction unit; wherein,
  • a parsing unit configured to parse the code stream to determine the prediction mode parameter of the current block; and when the prediction mode parameter indicates that the current block uses MIP to determine the intra prediction value, parse the code stream to determine the MIP parameter;
  • the parsing unit is further configured to analyze the code stream and determine the transform coefficient matrix and LFNST index number of the current block;
  • the second transformation unit is configured to, when the LFNST index number indicates that the current block uses LFNST, use LFNST to process the transformation coefficient matrix of the current block to obtain an LFNST output coefficient matrix;
  • the second determining unit is configured to determine the scanning order of LFNST coefficients used by the current block according to the MIP parameters
  • the second construction unit is configured to construct a first coefficient matrix using the LFNST output coefficient matrix according to the LFNST coefficient scanning order; wherein the LFNST coefficient scanning order includes a vertical scanning order and a horizontal scanning order.
  • an embodiment of the present application provides a decoder, which includes a second memory and a second processor; wherein,
  • the second memory is used to store a computer program that can run on the second processor
  • the second processor is configured to execute the method described in the second aspect when the computer program is running.
  • an embodiment of the present application provides a computer storage medium that stores a computer program that, when executed by a first processor, implements the method described in the first aspect, or is executed by a second
  • the processor implements the method described in the second aspect when executed.
  • the embodiments of the present application provide a transformation method, an encoder, a decoder, and a storage medium, which determine the prediction mode parameter of the current block; when the prediction mode parameter indicates that the current block uses the matrix-based intra prediction MIP to determine the intra prediction value , Determine the MIP parameters; determine the intra prediction value of the current block according to the MIP parameters, calculate the prediction difference between the current block and the intra prediction value; perform the first transformation on the prediction difference to obtain the first coefficient matrix; When the current block uses LFNST, determine the LFNST coefficient scanning order used by the current block according to the MIP parameters; use the first coefficient matrix to construct the input coefficient matrix of LFNST according to the LFNST coefficient scanning order; perform LFNST processing on the input coefficient matrix , The transformation coefficient matrix of the current block is obtained; wherein, the first transformation is a transformation different from LFNST, and the LFNST coefficient scanning order includes horizontal scanning order and vertical scanning order.
  • the selection of LFNST coefficient scanning order is more flexible, which not only improves the applicability of LFNST technology to non-traditional intra prediction modes, It also improves the coding and decoding efficiency, while also improving the video image quality.
  • Figure 1 is a schematic diagram of the application location of a LFNST technology provided by related technical solutions
  • FIG. 2A is a block diagram of a video encoding system provided by an embodiment of this application.
  • 2B is a block diagram of a video decoding system provided by an embodiment of this application.
  • FIG. 3 is a schematic flowchart of a conversion method provided by an embodiment of this application.
  • FIG. 4 is a flowchart of a MIP prediction process provided by an embodiment of this application.
  • 5A is a schematic structural diagram of a horizontal scanning sequence provided by an embodiment of this application.
  • 5B is a schematic structural diagram of a vertical scanning sequence provided by an embodiment of this application.
  • FIG. 6 is a schematic structural diagram of a calculation process of a matrix multiplication of LFNST technology provided by an embodiment of the application;
  • Figure 7A is a structural block diagram of an LFNST transform provided by related technical solutions.
  • Fig. 7B is a structural block diagram of another LFNST transform provided by related technical solutions.
  • FIG. 7C is a structural block diagram of yet another LFNST transform provided by related technical solutions.
  • Fig. 7D is a structural block diagram of yet another LFNST transform provided by related technical solutions.
  • FIG. 8 is a schematic flowchart of another conversion method provided by an embodiment of this application.
  • FIG. 9 is a flow chart of a specific process of LFNST according to an embodiment of the application.
  • FIG. 10 is a schematic diagram of the composition structure of an encoder provided by an embodiment of the application.
  • FIG. 11 is a schematic diagram of a specific hardware structure of an encoder provided by an embodiment of the application.
  • FIG. 12 is a schematic diagram of the composition structure of a decoder provided by an embodiment of the application.
  • FIG. 13 is a schematic diagram of a specific hardware structure of a decoder provided by an embodiment of the application.
  • the first image component, the second image component, and the third image component are generally used to represent the coding block (CB); among them, the three image components are a luminance component and a blue chrominance component. And a red chrominance component, specifically, the luminance component is usually represented by the symbol Y, the blue chrominance component is usually represented by the symbol Cb or U, and the red chrominance component is usually represented by the symbol Cr or V; in this way, the video image can be in YCbCr format It can also be expressed in YUV format.
  • CB coding block
  • the first image component may be a luminance component
  • the second image component may be a blue chrominance component
  • the third image component may be a red chrominance component
  • FIG. 1 shows a schematic diagram of the application position of an LFNST technology provided by related technical solutions.
  • LFNST technology is applied between the positive primary transformation unit 11 and the quantization unit 12, and between the inverse quantization unit 13 and the inverse primary transformation unit 14. LFNST technology.
  • the positive primary transformation unit 11 performs the first transformation (which can be called “Core Transform” or “primary transformation” or “ Primary transformation”) to obtain the transformation coefficient matrix after the first transformation; then perform LFNST transformation (may be called “Secondary Transform” or “secondary transformation") on the coefficients in the transformation coefficient matrix to obtain LFNST transformation coefficients
  • LFNST transformation may be called “Secondary Transform” or “secondary transformation”
  • the matrix is finally quantized by the quantization unit 12 for the LFNST transform coefficient matrix, and the final quantized value is written into the video bitstream.
  • the quantized value of the LFNST transform coefficient matrix can be obtained by parsing the code stream, and the quantized value is inversely quantized by the inverse quantization unit 13 (may be called "Scaling") to obtain the restoration of the LFNST transform coefficient matrix
  • the coefficient matrix can be obtained by performing the reverse LFNST transformation on the restored value; then the coefficient matrix is subjected to the inverse transformation corresponding to the "Core Transform" on the encoder side through the inverse primary transformation unit 14, and finally the residual restored value is obtained.
  • the standard only defines the “inverse transform” operation on the decoder side, so in the standard, the “inverse LFNST transform” is also called “LFNST transform”; here, in order to facilitate the transformation with the encoder side To distinguish, the "LFNST transform” on the encoder side can be called “forward LFNST transform”, and the “LFNST transform” on the decoder side can be called “reverse LFNST transform”.
  • the prediction residual of the current transform block can be transformed by a positive primary transformation to obtain primary transformation coefficients, and then part of the primary transformation coefficients can be transformed by matrix multiplication for secondary transformation, resulting in a smaller and more concentrated two.
  • the decoder is subjected to inverse quantization processing.
  • the inverse quantized coefficient is subjected to inverse secondary transformation through matrix multiplication, and then the inverse is reversed.
  • the coefficients after the second transformation are inversely transformed to recover the prediction residuals.
  • the scan order is currently selected according to the intra prediction mode.
  • the scanning order on the encoder side, it refers to the scanning order of filling the two-dimensional primary transform coefficients into the one-dimensional primary transform coefficient vector, and on the decoder side, it refers to filling the one-dimensional primary transform coefficient vector into the The scanning order of the two-dimensional inverse primary transformation coefficient matrix.
  • the value of the intra prediction mode indicator (which can be represented by predModeIntra) can be determined according to the number of the traditional intra prediction mode, and then the scanning order is determined as the horizontal scanning order according to the value of predModeIntra Vertical scanning order; but for non-traditional frame prediction modes, especially Matrix-based Intra Prediction (MIP) mode, the value of predModeIntra is directly set to indicate the intra prediction mode corresponding to PLANAR mode
  • MIP Matrix-based Intra Prediction
  • the index number ie 0) causes the current block in MIP mode to select only the horizontal scanning order, which makes the current block in MIP mode lack variability when performing LFNST transformation, which results in LFNST technology not being suitable for MIP mode, and It also reduces coding efficiency.
  • the embodiment of the present application provides a transformation method, which is applied to an encoder.
  • determining the prediction mode parameter of the current block when the prediction mode parameter indicates that the current block uses the matrix-based intra prediction MIP to determine the intra prediction value, the MIP parameter is determined; according to the MIP parameter, the intra prediction value of the current block is determined, and the calculated value is calculated.
  • the prediction difference between the current block and the intra-frame prediction value; the prediction difference value is transformed for the first time to obtain the first coefficient matrix; when the current block uses LFNST, the MIP parameter is used to determine the LFNST coefficient scanning order; according to the LFNST coefficient scanning order, use the first coefficient matrix to construct the input coefficient matrix of LFNST; perform LFNST processing on the input coefficient matrix to obtain the transformation coefficient matrix of the current block; among them, the first transformation is different from LFNST Conversion, LFNST coefficient scanning order includes horizontal scanning order and vertical scanning order.
  • the selection of LFNST coefficient scanning order is more flexible, which not only improves the applicability of LFNST technology to non-traditional intra prediction modes, It also improves the coding and decoding efficiency, while also improving the video image quality.
  • the video encoding system 10 includes a transform and quantization unit 101, an intra-frame estimation unit 102, and an intra-frame
  • the encoding unit 109 can implement header information encoding and context-based adaptive binary arithmetic coding (Context-based Adaptive Binary Arithmatic Coding, CABAC).
  • CABAC Context-based Adaptive Binary Arithmatic Coding
  • a video coding block can be obtained by dividing the coding tree unit (CTU), and then the residual pixel information obtained after intra-frame or inter-frame prediction is paired by the transformation and quantization unit 101
  • the video coding block is transformed, including transforming the residual information from the pixel domain to the transform domain, and quantizing the resulting transform coefficients to further reduce the bit rate;
  • the intra-frame estimation unit 102 and the intra-frame prediction unit 103 are used for Perform intra-frame prediction on the video encoding block; specifically, the intra-frame estimation unit 102 and the intra-frame prediction unit 103 are used to determine the intra-frame prediction mode to be used to encode the video encoding block;
  • the motion compensation unit 104 and the motion estimation unit 105 is used to perform inter-frame predictive coding of the received video coding block relative to one or more blocks in one or more reference frames to provide temporal prediction information;
  • the motion estimation performed by the motion estimation unit 105 is a method for generating a motion vector In the process, the motion vector can estimate the motion of
  • the context content can be based on adjacent coding blocks, can be used to encode information indicating the determined intra prediction mode, and output the code stream of the video signal; and the decoded image buffer unit 110 is used to store reconstructed video coding blocks for Forecast reference. As the video image encoding progresses, new reconstructed video encoding blocks will be continuously generated, and these reconstructed video encoding blocks will be stored in the decoded image buffer unit 110.
  • the video decoding system 20 includes a decoding unit 201, an inverse transform and inverse quantization unit 202, and an intra-frame
  • the prediction unit 203, the motion compensation unit 204, the filtering unit 205, and the decoded image buffer unit 206, etc. wherein the decoding unit 201 can implement header information decoding and CABAC decoding, and the filtering unit 205 can implement deblocking filtering and SAO filtering.
  • the code stream of the video signal is output; the code stream is input into the video decoding system 20, and first passes through the decoding unit 201 to obtain the decoded transform coefficient; the transform coefficient is passed through
  • the inverse transform and inverse quantization unit 202 performs processing to generate a residual block in the pixel domain; the intra prediction unit 203 can be used to generate data based on the determined intra prediction mode and the data from the previous decoded block of the current frame or picture The prediction data of the current video decoding block; the motion compensation unit 204 determines the prediction information for the video decoding block by analyzing the motion vector and other associated syntax elements, and uses the prediction information to generate the predictability of the video decoding block being decoded Block; by summing the residual block from the inverse transform and inverse quantization unit 202 and the corresponding predictive block generated by the intra prediction unit 203 or the motion compensation unit 204 to form a decoded video block; the decoded video signal Through the filtering unit 205 in order to remove the block effect artifacts, the video quality can
  • the transform method in the embodiment of this application can be applied to the transform and quantization unit 101 shown in FIG. 2A.
  • the transform and quantization unit 101 includes the positive primary transform unit 11 and the quantization unit 12 shown in FIG.
  • the transformation method is specifically applied to the part between transformation and quantization.
  • the transform method in the embodiment of the present application can also be applied to the inverse transform and inverse quantization unit 106 shown in FIG. 2A or the inverse transform and inverse quantization unit 202 shown in FIG. 2B, whether it is inverse transform or inverse quantization.
  • the inverse quantization unit 106 or the inverse transform and inverse quantization unit 202 can both include the inverse quantization unit 13 and the inverse primary transform unit 14 shown in FIG. 1.
  • the transform method is specifically applied to the part between inverse quantization and inverse transform.
  • the transformation method in the embodiment of this application can be applied to both a video encoding system, a video decoding system, or even a video encoding system and a video decoding system at the same time.
  • the embodiment of this application does not make specific details. limited.
  • the “current block” specifically refers to the current encoding block in intra prediction; when the transformation method is applied to a video decoding system, the “current block” specifically refers to Refers to the current decoded block in intra prediction.
  • FIG. 3 shows a schematic flowchart of a conversion method provided by an embodiment of the present application.
  • the method may include:
  • each image block currently to be encoded may be referred to as a coding block (CB).
  • each encoding block may include a first image component, a second image component, and a third image component; and the current block is the encoding of the first image component, the second image component, or the third image component currently to be predicted in the video image.
  • the current block is the encoding of the first image component, the second image component, or the third image component currently to be predicted in the video image.
  • the current block performs the first image component prediction, and the first image component is the brightness component, that is, the image component to be predicted is the brightness component, then the current block can also be called the brightness block; or, it is assumed that the current block performs the second image component Prediction, and the second image component is a chrominance component, that is, the image component to be predicted is a chrominance component, then the current block can also be called a chrominance block.
  • the prediction mode parameter indicates the coding mode of the current block and parameters related to the mode.
  • a rate-distortion optimization (Rate Distortion Optimization, RDO) method can be used to determine the prediction mode parameters of the current block.
  • the determining the prediction mode parameter of the current block may include:
  • a minimum rate-distortion cost result is selected from a plurality of calculated rate-distortion cost results, and a prediction mode corresponding to the minimum rate-distortion cost result is determined as the prediction mode parameter of the current block.
  • multiple prediction modes can be used for the current block to respectively encode the image components to be predicted.
  • multiple prediction modes usually include traditional intra prediction modes and non-traditional intra prediction modes, while traditional intra prediction modes can include direct current (DC) mode, planar (PLANAR) mode, angular mode, etc.
  • Non-traditional intra prediction modes can include MIP mode, Cross-component Linear Model Prediction (CCLM) mode, Intra Block Copy (IBC) mode and PLT (Palette) mode, etc. .
  • the rate-distortion cost result corresponding to each prediction mode can be obtained; then the minimum rate-distortion cost result is selected from the obtained multiple rate-distortion cost results, and The prediction mode corresponding to the minimum rate-distortion cost result is determined as the prediction mode parameter of the current block; in this way, the determined prediction mode can be used to encode the current block, and in this prediction mode, the prediction residual can be made small , Can improve coding efficiency.
  • S303 Determine the intra-frame prediction value of the current block according to the MIP parameter, and calculate the prediction difference between the current block and the intra-frame prediction value;
  • the input data for MIP prediction includes: the position of the current block (xTbCmp, yTbCmp), the MIP prediction mode applied to the current block (can be represented by modeId), and the height of the current block (in nTbH) Representation), the width of the current block (indicated by nTbW), and the transposition processing indication flag (which can be represented by isTransposed) whether transposition is needed, etc.;
  • the output data of MIP prediction includes: the prediction block of the current block, in the prediction block
  • the MIP prediction process can be divided into four steps: configuring core parameters 41, obtaining reference pixels 42, constructing input samples 43, and generating predicted values 44.
  • the core parameter 41 for configuring the core parameter 41, according to the size of the current block in the frame, the current block can be divided into three categories, and mipSizeId is used to record the type of the current block; and for different types of current blocks, refer to the number of sampling points and matrix multiplication output The number of sampling points is different.
  • the reference pixels 42 when predicting the current block, the upper block and the left block of the current block are already coded blocks at this time.
  • the reference pixels of the MIP technology are the reconstructed values of the upper row of pixels and the left column of the current block.
  • the process of obtaining the reference pixel adjacent to the upper side of the current block (indicated by refT) and the reference pixel adjacent to the left side (indicated by refL) is the process of obtaining the reference pixels.
  • this step is used for the input of matrix multiplication, and mainly includes: obtaining reference samples 431, constructing reference sampling buffer 432, and deriving matrix multiplication input samples 433; among them, the process of obtaining reference samples is downsampling Process, and the construction of the reference sampling buffer 432 may include the buffer filling mode 4321 when transposition is not required and the buffer filling mode 4322 when transposition is required.
  • this step is used to obtain the MIP predicted value of the current block, which may mainly include: constructing a matrix multiplication output sampling block 441, matrix multiplication output sampling clamp 442, matrix multiplication output sampling transposition 443, and generating MIP The final predicted value 444; wherein, the construction of the matrix multiplication output sampling block 441 may include obtaining the weight matrix 4411, obtaining the shift factor and the offset factor 4412, and the matrix multiplication operation 4413, and generating the MIP final predicted value 444 may also include generating unneeded upper The sampled predicted value 4441 and the generated predicted value 4442 that need to be up-sampled. In this way, after the four steps, the intra prediction value of the current block can be obtained.
  • the difference calculation can be performed according to the actual pixel value of the current block and the intra-frame prediction value, and the calculated difference value is used as the prediction difference value, which is convenient for subsequent prediction difference values. Transformation processing.
  • the MIP parameter may include a MIP transposition indicator parameter (which can be represented by isTransposed); here, the value of the MIP transposition indicator parameter is used to indicate whether to transpose the sampling point input vector used in the MIP mode. .
  • the adjacent reference sample set can be obtained according to the reference sample value corresponding to the adjacent reference pixel on the left side of the current block and the reference sample value corresponding to the adjacent reference pixel on the upper side; After the adjacent reference sample set, an input reference sample set can be constructed at this time, that is, the sampling point input vector used in the MIP mode.
  • an input reference sample set can be constructed at this time, that is, the sampling point input vector used in the MIP mode.
  • there is a difference between the encoder side and the decoder side which is mainly related to the value of the MIP transpose indicator parameter.
  • the utilization rate distortion optimization method can still be used to determine the value of the MIP transposition indicator parameter. Specifically, it may include:
  • the value of the MIP transposition indicator parameter can be determined to be 1 at this time;
  • the value of the MIP transposition indicator parameter can be determined to be 0 at this time.
  • the reference sample value corresponding to the upper side of the adjacent reference sample set can be stored before the reference sample value corresponding to the left side, At this time, there is no need to perform transposition processing, that is, there is no need to perform transposition processing on the sampling point input vector used in the MIP mode, and the buffer can be directly determined as the input reference sample value set; when the MIP transposition indicates the value of the parameter When it is 1, in the buffer, the reference sample value corresponding to the upper side of the adjacent reference sample set can be stored after the reference sample value corresponding to the left side.
  • the buffer is transposed, that is, it is necessary Transpose the input vector of the sampling points used in the MIP mode, and then determine the transposed buffer as the input reference sample value set. In this way, after the input reference sample value set is obtained, it can be used in the process of determining the intra prediction value corresponding to the current block in the MIP mode.
  • the MIP parameter may also include a MIP mode index number (which can be represented by modeId), where the MIP mode index number is used to indicate the MIP mode used by the current block, and the MIP mode is used to indicate the use of MIP to determine the The calculation and derivation method of the intra prediction value of the current block is described.
  • MIP mode index number which can be represented by modeId
  • MIP mode index number that is, different MIP modes have different MIP mode index numbers; in this way, according to the use MIP determines the calculation and derivation method of the intra-frame prediction value of the current block, and can determine the specific MIP mode, so that the corresponding MIP mode index number can be obtained; in this embodiment of the application, the value of the MIP mode index number can be 0, 1, 2, 3, 4, or 5.
  • the MIP parameters can also include parameters such as the size of the current block and the aspect ratio; among them, according to the size of the current block (that is, the width and height of the current block), the category of the current block can also be determined (you can use mipSizeId said).
  • determining the category of the current block according to the size of the current block may include:
  • the value of mipSizeId can be set to 0;
  • the value of mipSizeId can be set to 1;
  • the value of mipSizeId can be set to 2.
  • determining the category of the current block according to the size of the current block may include:
  • the value of mipSizeId can be set to 0;
  • the value of mipSizeId can be set to 1;
  • the value of mipSizeId can be set to 2.
  • the MIP parameters can also be determined, which is convenient for determining the LFNST transform core (which can be represented by the kernel) used by the current block according to the determined MIP parameters.
  • the first transformation is a transformation different from LFNST
  • the first coefficient matrix may be a two-dimensional primary transformation coefficient matrix.
  • the prediction difference is first transformed to obtain the first coefficient matrix, that is, the two-dimensional primary transform coefficient matrix; then the two-dimensional primary transform coefficients are scanned through the LFNST coefficient scanning order
  • the matrix is converted into a one-dimensional primary transformation coefficient matrix; the coefficients in the one-dimensional primary transformation coefficient matrix are transformed for the second time (that is, LFNST processing) to obtain the LFNST transformation coefficient matrix, and finally the LFNST transformation coefficient matrix is quantized and encoded , Write the obtained quantized value into the video bitstream.
  • LFNST can be performed on the current block only when the current block meets the following conditions at the same time. Among them, these conditions include: (a) the width and height of the current block are greater than or equal to 4; (b) the width and height of the current block are less than or equal to the maximum size of the transform block; (c) the current block or the current coding block
  • the prediction mode of is the intra prediction mode; (d) the primary transformation of the current block is two-dimensional forward primary transformation (DCT2) in both the horizontal and vertical directions; (e) the current block or the frame of the coding block where the current block is located
  • DCT2 two-dimensional forward primary transformation
  • the prediction mode is non-MIP mode or the prediction mode of the transform block is MIP mode, and the width and height of the transform block are both greater than or equal to 16. That is to say, for the current block in the embodiment of the present application, the above five conditions need to be met at the same time.
  • the LFNST coefficient scanning order includes a horizontal scanning order and a vertical scanning order.
  • the selected LFNST coefficient scanning order can be implicitly derived; for example, in the current H.266/VVC, the selected LFNST coefficient can be determined according to the intra prediction mode of the current block. The scan order of the LFNST coefficients.
  • the value of the intra prediction mode indicator (which can be represented by predModeIntra) can be determined, and the calculation formula is as follows:
  • the image component indicator (can be represented by cIdx) is used to indicate the luminance component or chrominance component of the current block; here, if the current block predicts the luminance component, then cIdx is equal to 0; if the current block predicts the chrominance component , Then cIdx is equal to 1.
  • (xTbY, yTbY) is the coordinates of the sampling point in the upper left corner of the current block
  • IntraPredModeY[xTbY][yTbY] is the intra prediction mode of the luminance component
  • IntraPredModeC[xTbY][yTbY] is the intra prediction mode of the chrominance component.
  • intra-frame prediction modes can be divided into traditional intra-frame prediction modes and non-traditional intra-frame prediction modes.
  • predModeIntra the information indicated by the value of predModeIntra is as follows:
  • predModeIntra can be INTRA_LT_CCLM
  • INTRA_L_CCLM or INTRA_T_CCLM (81, 82, 83 respectively in VVC);
  • the value of predModeIntra can be the index number of the used MIP mode
  • predModeIntra can be [0,66].
  • predModeIntra can also be set in the following manner:
  • the mode of the central luminance block corresponding to the luminance position of the current block is MIP mode, that is, intra_mip_flag[xTbY+nTbW/2][yTbY+nTbH/2] is 1, then the value of predMode Intra is set to Indicates the index number of the PLANAR mode (ie 0);
  • the value of predModeIntra is set to the index number indicating the DC mode (ie 1);
  • predModeIntra the value of predModeIntra to the value IntraPredModeY[xTbY+nTbW/2][yTbY+nTbH/2] of the mode index number of the central luminance block corresponding to the luminance position of the current block (such as the chrominance block);
  • predModeIntra can be directly set to the index number (that is, 0) indicating the PLANAR mode.
  • wide-angle mapping can be performed according to the size of the current block, and the traditional intra prediction mode [0,66] is extended to [-14,80]; specific mapping The process is as follows:
  • the LFNST coefficient scanning order can be determined according to the value of predModeIntra. Specifically, if the value of predModeIntra is less than or equal to 34, the elements in v[j] can be filled to d'[x][y] according to the horizontal scanning order (raster scan). Among them, the elements filled in d’[x][y] are as follows,
  • the elements in v[j] can be filled to d’[x][y] according to the order of vertical scanning (that is, the transposition order of raster scanning).
  • the elements filled in d’[x][y] are as follows,
  • the scan order used by the current block in the MIP mode can only select the horizontal scan order. This results in a lack of variability when performing LFNST in MIP mode, which reduces coding efficiency.
  • the scanning order of LFNST coefficients used in the current block can be determined in combination with the MIP parameters. At this time, the horizontal scanning order can be selected, and the vertical scanning order can also be selected, so that the LFNST in the MIP mode has variability and can be Improve coding efficiency.
  • the MIP parameters can include parameters such as the MIP transposition indication parameter (which can be represented by isTransposed), the MIP mode index number (which can be represented by modeId), the size of the current block, and the type of the current block (which can be represented by mipSizeId); the following will How to select the scanning order of the LFNST coefficients used by the current block according to the MIP parameters is described in detail.
  • the determining the current block uses according to the MIP parameter can include:
  • the LFNST coefficient scanning order is set to the vertical scanning order
  • the LFNST coefficient scanning order is set to the horizontal scanning order.
  • the determining the current block uses according to the MIP parameter can include:
  • the LFNST coefficient scanning order is set to the vertical scanning order
  • the LFNST coefficient scanning order is set to the horizontal scanning order.
  • the MIP transposition indicator parameter is used to indicate whether to transpose the input vector of the sampling point used in the MIP mode, and the LFNST coefficient scanning sequence includes the horizontal scanning sequence and the vertical scanning sequence, you can The MIP transpose indicates the value of the parameter to select the LFNST coefficient scanning order used in the current block.
  • the LFNST coefficient when the value of the MIP transposition indicator parameter is equal to 1, that is, when the value of the MIP transposition indicator parameter indicates that the sampling point input vector used in the MIP mode is transposed, the LFNST coefficient can be The scan sequence is set to the vertical scan sequence; when the value of the MIP transposition indicator parameter is equal to 0, that is, the value of the MIP transposition indicator parameter indicates that the sampling point input vector used in the MIP mode is not transposed, and the LFNST can be set at this time The coefficient scan order is set to the horizontal scan order.
  • the LFNST when the value of the MIP transposition indicator parameter is equal to 1, that is, when the value of the MIP transposition indicator parameter indicates that the sampling point input vector used in the MIP mode is transposed, the LFNST can be set at this time.
  • the coefficient scanning order is set to the horizontal scanning order; when the value of the MIP transposition indicator parameter is equal to 0, that is, the value of the MIP transposition indicator parameter indicates that the sampling point input vector used in the MIP mode is not to be transposed.
  • the LFNST coefficient scanning order is set to the vertical scanning order.
  • the determining the LFNST used by the current block according to the MIP parameter can include:
  • the LFNST coefficient scanning order is set to be equal to the LFNST coefficient scanning order corresponding to the preset value of the LFNST intra prediction mode index number.
  • the MIP mode index number is used to indicate the MIP mode used by the current block
  • the MIP mode is used to indicate the calculation and derivation method of using MIP to determine the intra prediction value of the current block; that is, according to the MIP mode index number , You can also determine the LFNST coefficient scanning order.
  • the MIP mode index number can also be converted to the value of the LFNST intra prediction mode index number (which can be represented by predModeIntra); and then the value of predModeIntra is determined Output LFNST coefficient scanning order, such as horizontal scanning order or vertical scanning order.
  • the determining the MIP parameter can include:
  • the method may further include:
  • the LFNST coefficient scanning order used by the current block is a horizontal scanning order, then the LFNST coefficient scanning order used by the current block is set as a vertical scanning order;
  • the scanning order of the LFNST coefficients used by the current block is the vertical scanning order, then the scanning order of the LFNST coefficients used by the current block is set as the horizontal scanning order.
  • the MIP mode index number is used to indicate the MIP mode used by the current block, and the MIP mode is used to indicate the calculation and derivation method of using MIP to determine the intra prediction value of the current block;
  • the value of the MIP transposition indicator parameter It is used to indicate whether to transpose the sampling point input vector used in the MIP mode; that is, the LFNST coefficient scanning order can be determined according to the combination of the MIP transposition indicator parameter and the MIP mode index number.
  • the LFNST coefficient scanning order used by the current block can be set to the horizontal scanning order; If the value of the indicator parameter is equal to 1, then the scan order of the LFNST coefficients used in the current block can be set to the vertical scan order; or, in some MIP modes, if the value of the indicator parameter of the MIP transpose is equal to 0, then you can set The LFNST coefficient scanning order used in the current block is set to the vertical scanning order; if the value of the MIP transposition indication parameter is equal to 1, then the LFNST coefficient scanning order used in the current block can be set to the horizontal scanning order, which is not specifically limited in the implementation of this application.
  • the MIP mode index number can also be converted to the value of the LFNST intra prediction mode index number (which can be represented by predModeIntra), and then the current block usage can be determined according to the value of predModeIntra
  • the value of the MIP transposition indicator parameter indicates that the sampling point input vector used in the MIP mode is transposed.
  • the MIP parameter includes at least the MIP mode index number (modeId)
  • modeId MIP mode index number
  • the value of the LFNST intra prediction mode index number can also be obtained by looking up the table Way to get.
  • the determining the value of the LFNST intra prediction mode index number according to the value of the MIP mode index number may include:
  • first lookup table uses a first lookup table to determine the value of the LFNST intra prediction mode index number corresponding to the value of the MIP mode index number, where the first lookup table contains at least two LFNST frames with different values One or more different MIP mode index numbers corresponding to the intra prediction mode index numbers.
  • the first look-up table (Look-Up Table1, LUT1) is used to reflect the correspondence between the MIP mode index number and the LFNST intra prediction mode index number, that is, the first look-up table contains at least two different values One or more different MIP mode index numbers corresponding to each of the LFNST intra prediction mode index numbers.
  • different MIP modes can correspond to different values of predModeIntra; in this way, the MIP mode index number is determined according to the MIP mode, and then the value of predModeIntra is determined according to the first lookup table; and then according to the value of predModeIntra, Determine the scanning order of the LFNST coefficients used in the current block.
  • the LFNST coefficient scanning order can also be directly determined according to the value of the MIP mode index number. At this time, it is no longer necessary to use the value of predModeIntra, that is, it is no longer necessary to determine the LFNST intra prediction mode index number according to the MIP mode index number. Value.
  • the determining, according to the MIP parameters, the scanning order of the LFNST coefficients used by the current block may include:
  • the LFNST coefficient scanning order is set to be equal to the LFNST coefficient scanning order corresponding to the preset value of the MIP mode index number.
  • the method may further include:
  • the second look-up table uses a second look-up table to determine the LFNST coefficient scanning order corresponding to the value of the MIP mode index number; wherein, the second look-up table contains at least one or more different LFNST coefficient scanning orders corresponding to different The index number of the MIP mode.
  • the method may further include:
  • the LFNST coefficient scanning order is set to the vertical scanning order.
  • the selected LFNST coefficient scan order can be determined according to the value of the MIP mode index number (modeId); here, the value of the MIP mode index number can include There are 0, 1, 2, 3, 4, and 5.
  • the LFNST coefficient scanning order when the MIP mode index number value is 0, the LFNST coefficient scanning order can be set to the horizontal scanning order; when the MIP mode index number value is 1, the LFNST coefficient scanning order can be set It is the vertical scanning order; when the MIP mode index number value is 2, the LFNST coefficient scanning order can be set to the horizontal scanning order; when the MIP mode index number value is 3, the LFNST coefficient scanning order can be set to vertical
  • the scanning order, etc., are not specifically limited in the embodiment of the present application.
  • the value of the MIP mode index number when the value of the MIP mode index number satisfies the preset integer range, for example, the value of the MIP mode index number can be 0, 1, 2, and the LFNST coefficient scan order can be set to the horizontal scan order ;
  • the value of the MIP mode index number when the value of the MIP mode index number does not meet the preset integer range, for example, the value of the MIP mode index number can be 3, 4, 5, and the LFNST coefficient scanning order can be set to the vertical scanning order, etc.
  • the scanning order of LFNST coefficients can be selected according to one or more combinations of information in MIP parameters; it can also be based on MIP parameters to compare with traditional intra prediction modes. According to the mapping angle, the scanning order of LFNST coefficients is selected.
  • the method may further include:
  • the LFNST coefficient scanning order used by the current block is set to the horizontal scanning order
  • the scan order of the LFNST coefficients used in the current block is set to the vertical scan order.
  • the prediction mode of the current block is a non-MIP mode
  • the value of predModeIntra can be determined according to the intra-frame prediction mode; then the scanning order of LFNST coefficients used by the current block can be determined according to the value of predModeIntra.
  • the method may also include:
  • the value of the LFNST index number is set to indicate that the value corresponding to the LFNST is used, and the value of the LFNST index number is written into the video bitstream.
  • the value of the LFNST index number can be set to indicate the value corresponding to the use of LFNST, and the value of the LFNST index number can be written into the video code stream; so
  • the value of the LFNST index number can be obtained by parsing the code stream, so that the decoder side can determine that the current block uses LFNST.
  • S307 Perform LFNST processing on the input coefficient matrix to obtain the transform coefficient matrix of the current block.
  • the LFNST coefficient scanning sequence may include a horizontal scanning sequence and a vertical scanning sequence.
  • the first coefficient matrix that is, the two-dimensional primary transformation coefficient matrix
  • the LFNST processing Get the transform coefficient matrix of the current block.
  • LFNST is based on direct matrix multiplication to apply inseparable transformations.
  • a simplified indivisible transform technique is used in the LFNST transform.
  • the main idea of the simplified inseparable transform technology is to map N-dimensional vectors to R-dimensional vectors in different spaces, where N/R (R ⁇ N) is the scaling factor; at this time, the simplified inseparable transform technology corresponds to the transformation
  • the matrix is an R ⁇ N matrix, as shown below,
  • FIG. 6 shows a structural schematic diagram of a calculation process of a matrix multiplication of LFNST technology provided by an embodiment of the present application.
  • (a) shows the calculation process of the forward LFNST transformation. After the primary transformation coefficient passes through the transformation matrix T, the secondary transformation coefficient can be obtained;
  • (b) shows the calculation process of the reverse LFNST transformation . After the inverse quadratic transformation coefficients are transposed by the transformation matrix T T , the inverse primary transformation coefficients can be obtained.
  • 16 coefficients will be input on the encoder side, and 16 or 8 coefficients will be output after the forward LFNST; while on the decoder side, 16 coefficients will be input Or 8 coefficients, 16 coefficients will be output; that is to say, the encoder and the decoder have the opposite number of inputs and outputs.
  • TU Transform unit
  • the forward LFNST process corresponding to the 4 ⁇ 4 transform block is shown in Fig. 7A.
  • the white block is the prediction difference
  • the gray block is the primary transform coefficient
  • the black block is the secondary transform coefficient; here, at the position of the “0” example, the encoder sets the transform coefficient to 0.
  • the transform matrix size used is 8 ⁇ 16
  • the 4 ⁇ 4 primary transform coefficients in the current transform block are all input
  • the output is 4 ⁇ 2 secondary transform coefficients.
  • the forward LFNST process corresponding to the 4 ⁇ N or N ⁇ 4 transform block is shown in Fig. 7B.
  • the white block is the prediction difference
  • the gray block is the primary transform coefficient
  • the black block is the secondary transform coefficient; here, for the 4 ⁇ N or N ⁇ 4 transform block, when the forward LFNST is used,
  • the transform matrix size is 16 ⁇ 16
  • the first 4 ⁇ 4 sub-block in the current transform block specifically, it is the uppermost sub-block for the 4 ⁇ N transform block, and the left-most sub-block for the N ⁇ 4 transform block
  • the primary transform coefficients within are used as input
  • the output is 4 ⁇ 4 secondary transform coefficients.
  • the encoder still sets the transform coefficient to 0.
  • the forward LFNST process corresponding to the 8 ⁇ 8 transform block is shown in Fig. 7C.
  • the white block is the prediction difference
  • the gray block is the primary transform coefficient
  • the black block is the secondary transform coefficient
  • the transform matrix size used is 8 ⁇ 48.
  • the primary transform coefficients of the first three 4 ⁇ 4 sub-blocks (that is, the three sub-blocks located in the upper left corner) in the current transform block are used as input, and the output is 4 ⁇ 2 secondary transform coefficients.
  • the encoder still sets the transform coefficient to 0.
  • the forward LFNST process corresponding to the transform block larger than 8 ⁇ 8 is shown in Fig. 7D.
  • the white block is the prediction difference
  • the gray block is the primary transformation coefficient
  • the black block is the secondary transformation coefficient
  • the transformation matrix size used is 48 ⁇ 16
  • the primary transform coefficients of the first three 4 ⁇ 4 sub-blocks (that is, the three sub-blocks located in the upper left corner) in the current transform block are used as input, and the output is 4 ⁇ 4 secondary transform coefficients.
  • the encoder still sets the transform coefficient to 0.
  • Fig. 7A or Fig. 7B or Fig. 7C or Fig. 7D implements related processing such as the primary transformation of the prediction difference and the secondary transformation of the LFNST.
  • the applicability of the LFNST technology to the current block using the MIP mode can be improved, so that the selection of the scanning order is more flexible.
  • the relevant information of the MIP parameters is introduced, and the characteristics of the current block are judged according to the MIP information, and then the scanning order is selected.
  • the transformation method is applied to VTM7.0, and the test is performed under All Intra conditions at 24 frame intervals. Based on the average bit rate change under the same peak signal to noise ratio (Peak Signal to Noise Ratio, PSNR), it can be tested at this time.
  • PSNR Peak Signal to Noise Ratio
  • the three image components (ie Y, Cb, and Cr) obtain BD-rate changes of -0.03%, 0.00%, and -0.01% respectively; especially on large-resolution sequences, there will be better performance, Specifically, a BD-rate change of -0.10% in Y can be achieved on Class A1, thereby improving coding efficiency.
  • This embodiment provides a transformation method, which is applied to an encoder.
  • determining the prediction mode parameter of the current block when the prediction mode parameter indicates that the current block uses the matrix-based intra prediction MIP to determine the intra prediction value, the MIP parameter is determined; according to the MIP parameter, the intra prediction value of the current block is determined, and the calculated value is calculated.
  • the prediction difference between the current block and the intra-frame prediction value; the prediction difference value is transformed for the first time to obtain the first coefficient matrix; when the current block uses LFNST, the MIP parameter is used to determine the LFNST coefficient scanning order; according to the LFNST coefficient scanning order, use the first coefficient matrix to construct the input coefficient matrix of LFNST; perform LFNST processing on the input coefficient matrix to obtain the transformation coefficient matrix of the current block; among them, the first transformation is different from LFNST Transformation, LFNST coefficient scanning order includes horizontal scanning order and vertical scanning order.
  • FIG. 8 shows a schematic flowchart of another conversion method provided by an embodiment of the present application. As shown in Figure 8, the method may include:
  • prediction mode parameter indicates the coding mode of the current block and parameters related to the mode.
  • prediction modes usually include traditional intra prediction modes and non-traditional intra prediction modes, while traditional intra prediction modes can include DC mode, PLANAR mode, and angle mode, etc., and non-traditional intra prediction modes can include MIP mode, CCLM mode, IBC mode and PLT mode, etc.
  • prediction mode of the current block can be determined, and the corresponding prediction mode parameters will be written into the code stream, and the encoder will transmit it to the decoder.
  • the intra prediction mode of the luminance or chrominance component of the current block or the coding block where the current block is located can be obtained by parsing the code stream.
  • the value of predModeIntra can be determined, and the calculation formula is as the aforementioned formula (1) .
  • the image component indicator (which can be represented by cIdx) is used to indicate the luminance component or chrominance component of the current block; here, if the current block predicts the luminance component, then cIdx is equal to 0; if the current block predicts Is the chrominance component, then cIdx is equal to 1.
  • (xTbY, yTbY) is the coordinates of the sampling point in the upper left corner of the current block
  • IntraPredModeY[xTbY][yTbY] is the intra prediction mode of the luminance component
  • IntraPredModeC[xTbY][yTbY] is the intra prediction mode of the chrominance component.
  • MIP parameters can include parameters such as MIP transposition indication parameters (which can be represented by isTransposed), MIP mode index number (which can be represented by modeId), the size of the current block, and the category of the current block (which can be represented by mipSizeId), etc. ; The values of these parameters can be obtained by parsing the code stream.
  • the value of isTransposed can be determined by parsing the code stream; when the value of isTransposed is equal to 1, the input vector of the sampling point used in the MIP mode needs to be transposed; when the value of isTransposed is equal to 0 , There is no need to transpose the sampling point input vector used in the MIP mode; that is, the MIP transposition indication parameter can be used to indicate whether to transpose the sampling point input vector used in the MIP mode.
  • the MIP mode index number (which can be represented by modeId) can also be determined; where the MIP mode index number can be used to indicate the MIP mode used by the current block, and the MIP mode can be used to indicate the use of MIP Determine the calculation and derivation method of the intra prediction value of the current block. That is to say, different MIP modes have different values of the corresponding MIP mode index number; here, the value of the MIP mode index number can be 0, 1, 2, 3, 4, or 5.
  • parameter information such as the size of the current block, the aspect ratio, and the category of the current block (which can be represented by mipSizeId) can also be determined.
  • mipSizeId the category of the current block
  • the value of the LFNST index number can be used to indicate whether the current block uses LFNST. Specifically, after the LFNST index sequence number is parsed, when the value of the LFNST index sequence number is equal to 0, it indicates that the current block does not use LFNST; and when the value of the LFNST index sequence number is greater than 0, it indicates that the current block uses LFNST. At this time, LFNST can be used to process the transform coefficient matrix of the current block.
  • the specific process of LFNST can be divided into four steps: configuring core parameters 91, intra prediction mode mapping 92, selecting transformation matrix 93, calculating matrix multiplication 94 and constructing a transformation coefficient matrix 95. step.
  • this step is used to determine the value of predModeIntra, which may mainly include: non-traditional intra prediction mode mapping 921 and wide angle mapping 922; for selecting the transformation matrix 93, this step It is used to select a transformation set and a transformation matrix, mainly including: selecting a transformation set 931, selecting a transformation matrix group 932, and selecting a transformation matrix size 933.
  • the core parameters 91 For configuring the core parameters 91, it is first necessary to configure the length of the input secondary transform coefficient vector for LFNST calculation (which can be expressed by nonZeroSize) and the length of the output primary transform coefficient vector (which can be expressed by nLfnstOutSzie). Among them, the values for nonZeroSize and nLfnstOutSzie are shown in Table 1.
  • Transform block size nonZeroSize nLfnstOutSzie 4 ⁇ 4 8 16 4 ⁇ N or N ⁇ 4 (N>4) 16 16 8 ⁇ 8 8 48 >8 ⁇ 8 16 48
  • nLfnstSize is as follows:
  • the intra-frame prediction mode of the luminance or chrominance component of the current block or the coding block where the current block is located can also be obtained.
  • the value of predModeIntra can be determined, and the calculation formula is as the aforementioned formula (1).
  • the inverse quantized coefficient d[x][y] at this time is the secondary transform coefficient.
  • the intra-frame prediction modes can be divided into traditional intra-frame prediction modes and non-traditional intra-frame prediction modes.
  • the information indicated by the value of predModeIntra is as follows:
  • predModeIntra can be INTRA_LT_CCLM, INTRA_L_CCLM or INTRA_T_CCLM (81, 82, 83 respectively in VVC), it indicates that the prediction mode of the current block is CCLM mode;
  • intra_mip_flag[xTbY][yTbY] is equal to 1 and cIdx is equal to 0, it indicates that the prediction mode of the current block is MIP mode, and the value of predModeIntra indicates the used MIP mode index number modeId;
  • predModeIntra can be [0,66], which indicates that the prediction mode of the current block is the traditional intra prediction mode.
  • the LFNST transform core candidate set index number is determined according to the serial number of the traditional intra prediction mode by parsing the code stream. At this time, if the prediction mode of the current block is CCLM mode and MIP mode, you can also set the value of predModeIntra as follows:
  • predModeIntra indicates INTRA_LT_CCLM, INTRA_L_CCLM or INTRA_T_CCLM (81, 82, 83 respectively in VVC),
  • the mode of the central luminance block corresponding to the luminance position of the current block is MIP mode, that is, intra_mip_flag[xTbY+nTbW/2][yTbY+nTbH/2] is 1, then the value of predMode Intra is set to Indicates the index number of the PLANAR mode (ie 0);
  • the value of predModeIntra is set to the index number indicating the DC mode (ie 1);
  • predModeIntra the value of predModeIntra to the value IntraPredModeY[xTbY+nTbW/2][yTbY+nTbH/2] of the mode index number of the central luminance block corresponding to the luminance position of the current block (such as the chrominance block);
  • intra_mip_flag[xTbY][yTbY] is equal to 1 and cIdx is equal to 0, that is, the prediction mode of the current block is MIP mode
  • the value of predModeIntra can be directly set to the index number (ie 0) indicating the PLANAR mode.
  • wide-angle mapping can also be performed according to the size of the current block, and the traditional intra prediction mode [0, 66] can be extended to [ -14,80];
  • the specific mapping process is as follows:
  • the value of the index number (which can be represented by SetIdx) in the LFNST transform core candidate set can be determined, and the specific value is shown in Table 2.
  • the LFNST transform set includes four transform core candidate sets (set0, set1, set2, set3), which correspond to the values of SetIdx as 0, 1, 2, and 3.
  • the LFNST transformation core candidate set includes two sets of transformation matrices (also called LFNST transformation cores).
  • the candidate set of LFNST transformation cores is determined After that, a group of LFNST transform cores needs to be selected from the LFNST transform core candidate set, that is, the transform matrix used when determining the current block LFNST.
  • a group of LFNST transform cores can be selected through RDCost, and the index number (which can be represented by lfnst_idx) corresponding to the LFNST transform core is written into the video code stream and transmitted to the decoder side. Therefore, on the decoder side, the value of lfnst_idx can be obtained by parsing the code stream; then, according to the value of lfnst_idx, the transformation matrix (transformation core) indicated by lfnst_idx can be selected from the LFNST transformation core candidate set.
  • the first group of LFNST transform cores that is, the first group of transform matrices
  • the LFNST transform core candidate set will be selected
  • the second set of LFNST transform cores that is, the second set of transform matrices
  • nLfnstOutSize 16x16
  • nLfnstOutSize 48
  • the specific calculation process of v[j] is as follows:
  • Clip3 is a clamp work, and the value of the coefficient can be limited between the two numbers below, as shown below,
  • S805 Determine the scanning order of LFNST coefficients used by the current block according to the MIP parameters
  • the MIP parameters can include parameters such as the MIP transposition indication parameter (which can be represented by isTransposed), the MIP mode index number (which can be represented by modeId), the size of the current block, and the type of the current block (which can be represented by mipSizeId); the following will How to select the LFNST transform core used by the current block according to the MIP parameters is described in detail.
  • the determining the LFNST coefficient scanning order used by the current block according to the MIP parameter may include:
  • the LFNST coefficient scanning order is set to the vertical scanning order
  • the LFNST coefficient scanning order is set to the horizontal scanning order.
  • the determining the LFNST coefficient scanning order used by the current block according to the MIP parameter may include:
  • the LFNST coefficient scanning order is set to the vertical scanning order
  • the LFNST coefficient scanning order is set to the horizontal scanning order.
  • the value of the MIP transposition indicator parameter is used to indicate whether to transpose the sampling point input vector used in the MIP mode, then after parsing the code stream, the value of the MIP transposition indicator parameter is obtained, The value of the indicator parameter can be MIP transposed to select the LFNST coefficient scanning order used in the current block.
  • the LFNST coefficient when the value of the MIP transposition indicator parameter is equal to 1, that is, when the value of the MIP transposition indicator parameter indicates that the sampling point input vector used in the MIP mode is transposed, the LFNST coefficient can be The scan sequence is set to the vertical scan sequence; when the value of the MIP transposition indicator parameter is equal to 0, that is, the value of the MIP transposition indicator parameter indicates that the sampling point input vector used in the MIP mode is not transposed, and the LFNST can be set at this time The coefficient scan order is set to the horizontal scan order.
  • the LFNST when the value of the MIP transposition indicator parameter is equal to 1, that is, when the value of the MIP transposition indicator parameter indicates that the sampling point input vector used in the MIP mode is transposed, the LFNST can be set at this time.
  • the coefficient scanning order is set to the horizontal scanning order; when the value of the MIP transposition indicator parameter is equal to 0, that is, the value of the MIP transposition indicator parameter indicates that the sampling point input vector used in the MIP mode is not to be transposed.
  • the LFNST coefficient scanning order is set to the vertical scanning order.
  • the determining the LFNST coefficient scanning order used by the current block according to the MIP parameter may include:
  • the LFNST coefficient scanning order is set to be equal to the LFNST coefficient scanning order corresponding to the preset value of the LFNST intra prediction mode index number.
  • the MIP mode index number is used to indicate the MIP mode used by the current block
  • the MIP mode is used to indicate the calculation and derivation method of using MIP to determine the intra prediction value of the current block; that is, according to the MIP mode index number , You can also determine the LFNST coefficient scanning order.
  • the MIP mode index number can also be converted to the value of the LFNST intra prediction mode index number (which can be represented by predModeIntra); and then according to the value of predModeIntra Take the value to determine the LFNST coefficient scan order, such as the horizontal scan order or the vertical scan order.
  • the LFNST coefficient scanning order used by the current block is determined according to the MIP parameter , Can include:
  • the method may further include:
  • the LFNST coefficient scanning order used by the current block is a horizontal scanning order, then the LFNST coefficient scanning order used by the current block is set as a vertical scanning order;
  • the scanning order of the LFNST coefficients used by the current block is the vertical scanning order, then the scanning order of the LFNST coefficients used by the current block is set as the horizontal scanning order.
  • the MIP mode index number is used to indicate the MIP mode used by the current block, and the MIP mode is used to indicate the calculation and derivation method of using MIP to determine the intra prediction value of the current block;
  • the value of the MIP transposition indicator parameter It is used to indicate whether to transpose the sampling point input vector used in the MIP mode; that is, the LFNST coefficient scanning order can be determined according to the combination of the MIP transposition indicator parameter and the MIP mode index number.
  • the MIP mode index number can also be converted to the value of the LFNST intra prediction mode index number (which can be represented by predModeIntra), and then the current block usage can be determined according to the value of predModeIntra
  • the value of the MIP transpose indicator parameter indicates that the sampling point input vector used in the MIP mode is transposed
  • the LFNST coefficient scanning sequence used by the current block is the horizontal scanning sequence
  • the LFNST coefficient scanning order used by the current block can be set to the vertical scanning order; if the LFNST coefficient scanning order used by the current block is the vertical scanning order, then the LFNST coefficient scanning order used by the current block can be set to the horizontal scanning order.
  • the MIP parameter includes at least the MIP mode index number (modeId)
  • modeId MIP mode index number
  • the value of the LFNST intra prediction mode index number can also be obtained by looking up the table Way to get.
  • the determining the value of the LFNST intra prediction mode index number according to the value of the MIP mode index number may include:
  • first lookup table uses a first lookup table to determine the value of the LFNST intra prediction mode index number corresponding to the value of the MIP mode index number, where the first lookup table contains at least two LFNST frames with different values One or more different MIP mode index numbers corresponding to the intra prediction mode index numbers.
  • the first look-up table (Look-Up Table1, LUT1) is used to reflect the correspondence between the MIP mode index number and the LFNST intra prediction mode index number, that is, the first look-up table contains at least two different values One or more different MIP mode index numbers corresponding to each of the LFNST intra prediction mode index numbers.
  • different MIP modes can correspond to different values of predModeIntra; in this way, the MIP mode index number is determined according to the MIP mode, and then the value of predModeIntra is determined according to the first lookup table; and then according to the value of predModeIntra, Determine the scanning order of the LFNST coefficients used in the current block.
  • the LFNST coefficient scanning order can also be directly determined according to the value of the MIP mode index number. At this time, it is no longer necessary to use the value of predModeIntra, that is, it is no longer necessary to determine the LFNST intra prediction mode index number according to the MIP mode index number. Value.
  • the determining, according to the MIP parameters, the scanning order of the LFNST coefficients used by the current block may include:
  • the LFNST coefficient scanning order is set to be equal to the LFNST coefficient scanning order corresponding to the preset value of the MIP mode index number.
  • the method may further include:
  • the second look-up table uses a second look-up table to determine the LFNST coefficient scanning order corresponding to the value of the MIP mode index number; wherein, the second look-up table contains at least one or more different LFNST coefficient scanning orders corresponding to different The index number of the MIP mode.
  • the method may further include:
  • the LFNST coefficient scanning order is set to the vertical scanning order.
  • the selected LFNST coefficient scan order can be determined according to the value of the MIP mode index number (modeId); here, the value of the MIP mode index number can include There are 0, 1, 2, 3, 4, and 5.
  • the LFNST coefficient scanning order when the MIP mode index number value is 0, the LFNST coefficient scanning order can be set to the horizontal scanning order; when the MIP mode index number value is 1, the LFNST coefficient scanning order can be set It is the vertical scanning order; when the MIP mode index number value is 2, the LFNST coefficient scanning order can be set to the horizontal scanning order; when the MIP mode index number value is 3, the LFNST coefficient scanning order can be set to vertical
  • the scanning order, etc., are not specifically limited in the embodiment of the present application.
  • the value of the MIP mode index number when the value of the MIP mode index number satisfies the preset integer range, for example, the value of the MIP mode index number can be 0, 1, 2, and the LFNST coefficient scan order can be set to the horizontal scan order ;
  • the value of the MIP mode index number when the value of the MIP mode index number does not meet the preset integer range, for example, the value of the MIP mode index number can be 3, 4, 5, and the LFNST coefficient scanning order can be set to the vertical scanning order, etc.
  • the scanning order of LFNST coefficients can be selected according to one or more combinations of information in MIP parameters; it can also be based on MIP parameters to compare with traditional intra prediction modes. According to the mapping angle, the scanning order of LFNST coefficients is selected.
  • the scanning order of LFNST coefficients can also be selected according to one or more information combinations in MIP parameters; it can also be compared with traditional intra prediction based on MIP parameters. For the mapping between the modes, the scanning order of the LFNST coefficients is then selected according to the mapped angle, which is not specifically limited in the embodiment of the present application.
  • the method may further include:
  • the LFNST coefficient scanning order used by the current block is set to the horizontal scanning order
  • the scan order of the LFNST coefficients used in the current block is set to the vertical scan order.
  • the prediction mode of the current block is a non-MIP mode
  • the value of predModeIntra can be determined according to the intra-frame prediction mode; then the scanning order of LFNST coefficients used by the current block can be determined according to the value of predModeIntra.
  • S806 Construct a first coefficient matrix using the LFNST output coefficient matrix according to the LFNST coefficient scanning order.
  • the LFNST coefficient scanning order includes a vertical scanning order and a horizontal scanning order.
  • the LFNST output coefficient matrix can be used to construct the first coefficient matrix; here, the first coefficient matrix can be a two-dimensional primary transformation coefficient matrix.
  • the method may further include:
  • the first coefficient matrix can be transformed for the first time to obtain the predicted difference of the current block; here, the first transformation is a transformation process different from LFNST.
  • the prediction mode parameters of the current block are determined by analyzing the code stream, if the prediction mode is MIP mode, the current block can also be predicted according to the MIP mode to obtain the intra prediction value of the current block; and then according to the intra prediction The value and the prediction difference are summed, and then the obtained sum value is used as the reconstruction value of the current block, which also realizes the encoding and decoding processing of the current block, and can restore the original value of the current block.
  • the applicability of the LFNST technology to the current block using the MIP mode can be improved, so that the selection of the scanning order is more flexible.
  • the relevant information of the MIP parameters is introduced, and the characteristics of the current block are judged according to the MIP information, and then the scanning order is selected.
  • the conversion method is applied to VTM7.0, and tested under All Intra conditions at 24 frame intervals, based on the average bit rate change under the same peak signal to noise ratio (Peak Signal to Noise Ratio, PSNR).
  • the three image components (ie Y, Cb, and Cr) obtain BD-rate changes of -0.03%, 0.00%, and -0.01% respectively; especially on large-resolution sequences, there will be better performance, Specifically, a BD-rate change of -0.10% in Y can be achieved on Class A1, thereby improving decoding efficiency.
  • This embodiment provides a transformation method, which is applied to a decoder. Determine the prediction mode parameter of the current block by parsing the code stream; and when the prediction mode parameter indicates that the current block uses MIP to determine the intra prediction value, parse the code stream to determine the MIP parameter; parse the code stream to determine the current The transform coefficient matrix of the block and the LFNST index number; when the LFNST index number indicates that the current block uses LFNST, the transform coefficient matrix of the current block is processed using LFNST to obtain the LFNST output coefficient matrix; according to the MIP parameter , Determine the LFNST coefficient scan order used by the current block; according to the LFNST coefficient scan order, use the LFNST output coefficient matrix to construct a first coefficient matrix; wherein the LFNST coefficient scan order includes a vertical scan order and a horizontal scan order .
  • FIG. 10 shows a schematic diagram of the composition structure of an encoder 100 provided by an embodiment of the present application.
  • the encoder 100 may include: a first determination unit 1001, a first calculation unit 1002, a first transformation unit 1003, and a first construction unit 1004; wherein,
  • the first determining unit 1001 is configured to determine the prediction mode parameter of the current block; and when the prediction mode parameter indicates that the current block uses MIP to determine the intra prediction value, determine the MIP parameter;
  • the first calculation unit 1002 is configured to determine the intra prediction value of the current block according to the MIP parameter, and calculate the prediction difference between the current block and the intra prediction value;
  • the first transformation unit 1003 is configured to perform a first transformation on the prediction difference to obtain a first coefficient matrix
  • the first determining unit 1001 is further configured to determine the scanning order of LFNST coefficients used by the current block according to the MIP parameters when the current block uses LFNST;
  • the first construction unit 1004 is configured to construct an input coefficient matrix of LFNST by using the first coefficient matrix according to the scanning order of the LFNST coefficients;
  • the first transformation unit 1003 is further configured to perform LFNST processing on the input coefficient matrix to obtain the transformation coefficient matrix of the current block; wherein, the first transformation is a transformation different from LFNST, and the LFNST coefficient scanning order Including horizontal scanning order and vertical scanning order.
  • the MIP parameter includes a MIP transposition indicator parameter, wherein the value of the MIP transposition indicator parameter is used to indicate whether to transpose the sampling point input vector used in the MIP mode.
  • the encoder 100 may further include a first transposition unit 1005 configured to perform transposition processing on the sampling point input vector used in the MIP mode when the value of the MIP transposition indication parameter indicates , Setting the LFNST coefficient scanning sequence to the vertical scanning sequence; and when the value of the MIP transposition indication parameter indicates that the sampling point input vector used in the MIP mode is not to be transposed, the LFNST coefficient scanning sequence is set It is the horizontal scanning sequence.
  • a first transposition unit 1005 configured to perform transposition processing on the sampling point input vector used in the MIP mode when the value of the MIP transposition indication parameter indicates , Setting the LFNST coefficient scanning sequence to the vertical scanning sequence; and when the value of the MIP transposition indication parameter indicates that the sampling point input vector used in the MIP mode is not to be transposed, the LFNST coefficient scanning sequence is set It is the horizontal scanning sequence.
  • the first transposition unit 1005 is further configured to set the LFNST coefficient scanning order when the value of the MIP transposition indication parameter indicates that the sampling point input vector used in the MIP mode is transposed Is a horizontal scanning sequence; and when the value of the MIP transposition indication parameter indicates that the sampling point input vector used in the MIP mode is not to be transposed, the LFNST coefficient scanning sequence is set to the vertical scanning sequence.
  • the MIP parameters include a MIP mode index sequence number, wherein the MIP mode index sequence number is used to indicate the MIP mode used by the current block, and the MIP mode is used to indicate the MIP mode used to determine the current block.
  • the calculation and derivation method of intra prediction value is used to indicate the MIP mode used by the current block.
  • the encoder 100 may further include a first setting unit 1006, where:
  • the first determining unit 1001 is further configured to determine the value of the LFNST intra prediction mode index number according to the value of the MIP mode index number;
  • the first setting unit 1006 is configured to set the LFNST coefficient scanning order equal to the LFNST coefficient scanning order corresponding to the preset value of the LFNST intra prediction mode index number.
  • the first determining unit 1001 is further configured to use a first lookup table to determine the value of the LFNST intra prediction mode index number corresponding to the value of the MIP mode index number, wherein the first The look-up table contains at least one or more different MIP mode index numbers corresponding to two LFNST intra prediction mode index numbers with different values.
  • the first setting unit 1006 is further configured to set the LFNST coefficient scanning order equal to the LFNST coefficient scanning order corresponding to the preset value of the MIP mode index number.
  • the first determining unit 1001 is further configured to use a second look-up table to determine the LFNST coefficient scanning order corresponding to the value of the MIP mode index number; wherein, the second look-up table contains at least the different One or more different MIP mode index numbers corresponding to the scanning sequence of the LFNST coefficients.
  • the first setting unit 1006 is further configured to set the LFNST coefficient scanning order to the horizontal scanning order when the value of the MIP mode index number is within a preset range of one or more integers; And when the value of the MIP mode index number is not within the preset range of one or more integers, the LFNST coefficient scanning order is set to the vertical scanning order.
  • the MIP parameter further includes a MIP transposition indicator parameter, and the value of the MIP transposition indicator parameter is used to indicate whether to transpose the sampling point input vector used in the MIP mode;
  • the first transposition unit 1005 is further configured to, when the value of the MIP transposition indication parameter indicates that the sampling point input vector used in the MIP mode is transposed, if the scanning order of the LFNST coefficients used in the current block is horizontal Scan order, the LFNST coefficient scan order used by the current block is set to the vertical scan order; and if the LFNST coefficient scan order used by the current block is the vertical scan order, the LFNST coefficient scan order used by the current block is set Set to horizontal scan order.
  • the first setting unit 1006 is further configured to set the value of the LFNST index sequence number to indicate the value corresponding to the use of LFNST, and write the value of the LFNST index sequence number into the video bitstream.
  • a "unit" may be a part of a circuit, a part of a processor, a part of a program or software, etc., of course, may also be a module, or may also be non-modular.
  • the various components in this embodiment may be integrated into one processing unit, or each unit may exist alone physically, or two or more units may be integrated into one unit.
  • the above-mentioned integrated unit can be realized in the form of hardware or software function module.
  • the integrated unit is implemented in the form of a software function module and is not sold or used as an independent product, it can be stored in a computer readable storage medium.
  • the technical solution of this embodiment is essentially or It is said that the part that contributes to the existing technology or all or part of the technical solution can be embodied in the form of a software product.
  • the computer software product is stored in a storage medium and includes several instructions to enable a computer device (which can A personal computer, a server, or a network device, etc.) or a processor (processor) executes all or part of the steps of the method described in this embodiment.
  • the aforementioned storage media include: U disk, mobile hard disk, read only memory (Read Only Memory, ROM), random access memory (Random Access Memory, RAM), magnetic disk or optical disk and other media that can store program codes.
  • an embodiment of the present application provides a computer storage medium for use in the encoder 100.
  • the computer storage medium stores a transformation program that, when executed by a first processor, implements any one of the foregoing embodiments. Methods.
  • FIG. 11 shows an example of a specific hardware structure of the encoder 100 provided by an embodiment of the present application, which may include: a first communication interface 1101, a first memory 1102, and a first communication interface 1101; A processor 1103; various components are coupled together through a first bus system 1104.
  • the first bus system 1104 is used to implement connection and communication between these components.
  • the first bus system 1104 also includes a power bus, a control bus, and a status signal bus.
  • various buses are marked as the first bus system 1104 in FIG. 11. among them,
  • the first communication interface 1101 is used for receiving and sending signals in the process of sending and receiving information with other external network elements;
  • the first memory 1102 is configured to store a computer program that can run on the first processor 1103;
  • the first processor 1103 is configured to execute the following when running the computer program:
  • the first transform is a transform different from LFNST
  • the LFNST coefficient scanning order includes a horizontal scanning order and a vertical scanning order.
  • the first memory 1102 in the embodiment of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memory.
  • the non-volatile memory can be read-only memory (Read-Only Memory, ROM), programmable read-only memory (Programmable ROM, PROM), erasable programmable read-only memory (Erasable PROM, EPROM), and electrically available Erase programmable read-only memory (Electrically EPROM, EEPROM) or flash memory.
  • the volatile memory may be a random access memory (Random Access Memory, RAM), which is used as an external cache.
  • RAM static random access memory
  • DRAM dynamic random access memory
  • DRAM synchronous dynamic random access memory
  • DDRSDRAM Double Data Rate Synchronous Dynamic Random Access Memory
  • Enhanced SDRAM, ESDRAM Synchronous Link Dynamic Random Access Memory
  • Synchlink DRAM Synchronous Link Dynamic Random Access Memory
  • DRRAM Direct Rambus RAM
  • the first processor 1103 may be an integrated circuit chip with signal processing capability. In the implementation process, the steps of the foregoing method can be completed by an integrated logic circuit of hardware in the first processor 1103 or instructions in the form of software.
  • the above-mentioned first processor 1103 may be a general-purpose processor, a digital signal processor (Digital Signal Processor, DSP), an application specific integrated circuit (ASIC), a ready-made programmable gate array (Field Programmable Gate Array, FPGA) Or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components.
  • DSP Digital Signal Processor
  • ASIC application specific integrated circuit
  • FPGA ready-made programmable gate array
  • the methods, steps, and logical block diagrams disclosed in the embodiments of the present application can be implemented or executed.
  • the general-purpose processor may be a microprocessor or the processor may also be any conventional processor or the like.
  • the steps of the method disclosed in the embodiments of the present application may be directly embodied as being executed and completed by a hardware decoding processor, or executed and completed by a combination of hardware and software modules in the decoding processor.
  • the software module can be located in a mature storage medium in the field, such as random access memory, flash memory, read-only memory, programmable read-only memory, or electrically erasable programmable memory, registers.
  • the storage medium is located in the first memory 1102, and the first processor 1103 reads the information in the first memory 1102, and completes the steps of the foregoing method in combination with its hardware.
  • the embodiments described in this application can be implemented by hardware, software, firmware, middleware, microcode, or a combination thereof.
  • the processing unit can be implemented in one or more application specific integrated circuits (ASIC), digital signal processor (Digital Signal Processing, DSP), digital signal processing equipment (DSP Device, DSPD), programmable Logic device (Programmable Logic Device, PLD), Field-Programmable Gate Array (Field-Programmable Gate Array, FPGA), general-purpose processors, controllers, microcontrollers, microprocessors, and others for performing the functions described in this application Electronic unit or its combination.
  • ASIC application specific integrated circuits
  • DSP Digital Signal Processing
  • DSP Device digital signal processing equipment
  • PLD programmable Logic Device
  • PLD Field-Programmable Gate Array
  • FPGA Field-Programmable Gate Array
  • the technology described in this application can be implemented through modules (for example, procedures, functions, etc.) that perform the functions described in this application.
  • the software codes can be stored in the memory and executed by
  • the first processor 1103 is further configured to execute the method described in any one of the foregoing embodiments when the computer program is running.
  • This embodiment provides an encoder, which may include a first determination unit, a first calculation unit, a first transformation unit, and a first construction unit;
  • the introduction of MIP parameters during LFNST transformation makes the selection of LFNST coefficient scanning order more flexible, which not only improves the applicability of LFNST technology to non-traditional intra prediction modes, but also improves coding efficiency and at the same time improves video image quality.
  • FIG. 12 shows a schematic diagram of the composition structure of a decoder 120 provided by an embodiment of the present application.
  • the decoder 120 may include: an analysis unit 1201, a second transformation unit 1202, a second determination unit 1203, and a second construction unit 1204;
  • the parsing unit 1201 is configured to parse the code stream to determine the prediction mode parameter of the current block; and when the prediction mode parameter indicates that the current block uses MIP to determine the intra prediction value, parse the code stream to determine the MIP parameter;
  • the parsing unit 1201 is further configured to analyze the code stream and determine the transform coefficient matrix and LFNST index number of the current block;
  • the second transformation unit 1202 is configured to, when the LFNST index number indicates that the current block uses LFNST, use LFNST to process the transformation coefficient matrix of the current block to obtain an LFNST output coefficient matrix;
  • the second determining unit 1203 is configured to determine the scanning order of LFNST coefficients used by the current block according to the MIP parameters;
  • the second construction unit 1204 is configured to construct a first coefficient matrix using the LFNST output coefficient matrix according to the LFNST coefficient scanning order; wherein the LFNST coefficient scanning order includes a vertical scanning order and a horizontal scanning order.
  • the MIP parameter includes a MIP transposition indicator parameter, wherein the value of the MIP transposition indicator parameter is used to indicate whether to transpose the sampling point input vector used in the MIP mode.
  • the decoder 120 may further include a second transposition unit 1205, configured to perform transposition processing on the sampling point input vector used in the MIP mode when the value of the MIP transposition indication parameter indicates , Setting the LFNST coefficient scanning sequence to the vertical scanning sequence; and when the value of the MIP transposition indication parameter indicates that the sampling point input vector used in the MIP mode is not to be transposed, the LFNST coefficient scanning sequence is set It is the horizontal scanning sequence.
  • a second transposition unit 1205 configured to perform transposition processing on the sampling point input vector used in the MIP mode when the value of the MIP transposition indication parameter indicates , Setting the LFNST coefficient scanning sequence to the vertical scanning sequence; and when the value of the MIP transposition indication parameter indicates that the sampling point input vector used in the MIP mode is not to be transposed, the LFNST coefficient scanning sequence is set It is the horizontal scanning sequence.
  • the second transposition unit 1205 is further configured to set the LFNST coefficient scanning order when the value of the MIP transposition indication parameter indicates that the sampling point input vector used in the MIP mode is transposed. Is a horizontal scanning sequence; and when the value of the MIP transposition indication parameter indicates that the sampling point input vector used in the MIP mode is not to be transposed, the LFNST coefficient scanning sequence is set to the vertical scanning sequence.
  • the MIP parameters include a MIP mode index sequence number, wherein the MIP mode index sequence number is used to indicate the MIP mode used by the current block, and the MIP mode is used to indicate the MIP mode used to determine the current block.
  • the calculation and derivation method of intra prediction value is used to indicate the MIP mode used by the current block.
  • the decoder 120 may further include a second setting unit 1206, where:
  • the second determining unit 1203 is further configured to determine the value of the LFNST intra prediction mode index number according to the value of the MIP mode index number;
  • the second setting unit 1206 is configured to set the LFNST coefficient scanning order to be equal to the LFNST coefficient scanning order corresponding to the preset value of the LFNST intra prediction mode index number.
  • the second determining unit 1203 is further configured to use a first lookup table to determine the value of the LFNST intra prediction mode index number corresponding to the value of the MIP mode index number, wherein the first The look-up table contains at least one or more different MIP mode index numbers corresponding to two LFNST intra prediction mode index numbers with different values.
  • the second setting unit 1206 is further configured to set the LFNST coefficient scanning order equal to the LFNST coefficient scanning order corresponding to the preset value of the MIP mode index number.
  • the second determining unit 1203 is further configured to use a second look-up table to determine the LFNST coefficient scanning order corresponding to the value of the MIP mode index sequence number; wherein, the second look-up table contains at least the different One or more different MIP mode index numbers corresponding to the scanning sequence of the LFNST coefficients.
  • the second setting unit 1206 is further configured to set the LFNST coefficient scanning order to the horizontal scanning order when the value of the MIP mode index number is within a preset range of one or more integers; And when the value of the MIP mode index number is not within the preset range of one or more integers, the LFNST coefficient scanning order is set to the vertical scanning order.
  • the MIP parameter further includes a MIP transposition indicator parameter, and the value of the MIP transposition indicator parameter is used to indicate whether to transpose the sampling point input vector used in the MIP mode;
  • the second transposition unit 1205 is further configured to, when the value of the MIP transposition indication parameter indicates that the sampling point input vector used in the MIP mode is transposed, if the scanning order of the LFNST coefficients used in the current block is horizontal Scan order, the LFNST coefficient scan order used by the current block is set to the vertical scan order; and if the LFNST coefficient scan order used by the current block is the vertical scan order, the LFNST coefficient scan order used by the current block is set Set to horizontal scan order.
  • the decoder 120 may further include a second calculation unit 1207, where:
  • the second construction unit 1204 is configured to construct the intra prediction value of the current block according to the MIP parameter
  • the second transformation unit 1202 is configured to perform transformation processing different from LFNST on the first coefficient matrix to obtain the prediction difference of the current block;
  • the second calculation unit 1207 is configured to calculate the sum of the intra prediction value and the prediction difference, and use the sum as the reconstruction value of the current block.
  • a "unit" may be a part of a circuit, a part of a processor, a part of a program or software, etc., of course, it may also be a module, or it may also be non-modular.
  • the various components in this embodiment may be integrated into one processing unit, or each unit may exist alone physically, or two or more units may be integrated into one unit.
  • the above-mentioned integrated unit can be realized in the form of hardware or software function module.
  • the integrated unit is implemented in the form of a software function module and is not sold or used as an independent product, it can be stored in a computer readable storage medium.
  • this embodiment provides a computer storage medium, which is applied to the decoder 120.
  • the computer storage medium stores a transformation program, and when the transformation program is executed by the second processor, any one of the preceding embodiments is implemented. The method described.
  • FIG. 13 shows an example of a specific hardware structure of the decoder 120 provided by an embodiment of the present application, which may include: a second communication interface 1301, a second memory 1302, and a Two processors 1303; the components are coupled together through the second bus system 1304.
  • the second bus system 1304 is used to implement connection and communication between these components.
  • the second bus system 1304 also includes a power bus, a control bus, and a status signal bus.
  • various buses are marked as the second bus system 1304 in FIG. 13. among them,
  • the second communication interface 1301 is used for receiving and sending signals in the process of sending and receiving information with other external network elements;
  • the second memory 1302 is configured to store a computer program that can run on the second processor 1303;
  • the second processor 1303 is configured to execute: when the computer program is running:
  • the prediction mode parameter indicates that the current block uses MIP to determine the intra-frame prediction value, parse the code stream to determine the MIP parameter;
  • the LFNST output coefficient matrix is used to construct a first coefficient matrix; wherein the LFNST coefficient scanning order includes a vertical scanning order and a horizontal scanning order.
  • the second processor 1303 is further configured to execute the method described in any one of the foregoing embodiments when running the computer program.
  • the hardware function of the second memory 1302 is similar to that of the first memory 1102, and the hardware function of the second processor 1303 is similar to that of the first processor 1103; it will not be described in detail here.
  • This embodiment provides a decoder, which may include a parsing unit, a second transformation unit, a second determination unit, and a second construction unit; in this way, for the current block in the MIP mode, since the LFNST transformation is being performed MIP parameters are introduced to make the selection of LFNST coefficient scanning order more flexible, which not only improves the applicability of LFNST technology to non-traditional intra prediction modes, but also improves decoding efficiency and at the same time improves video image quality.
  • the prediction mode parameter of the current block is first determined; when the prediction mode parameter indicates that the current block uses matrix-based intra prediction MIP to determine the intra prediction value, the MIP parameter is determined; and the MIP parameter is determined according to the MIP parameter Intra prediction value, calculate the prediction difference between the current block and the intra prediction value; then perform the first transformation on the prediction difference to obtain the first coefficient matrix; when the current block uses LFNST, according to the MIP parameter Determine the scan order of the LFNST coefficients used in the current block; then use the first coefficient matrix to construct the input coefficient matrix of LFNST according to the scan order of the LFNST coefficients; finally perform LFNST processing on the input coefficient matrix to obtain the transform coefficient matrix of the current block;
  • the secondary transformation is different from LFNST, and the LFNST coefficient scanning order includes a horizontal scanning order and a vertical scanning order.
  • the selection of LFNST coefficient scanning order is more flexible, which not only improves the applicability of LFNST technology to non-traditional intra prediction modes, It also improves the coding and decoding efficiency, while also improving the video image quality.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Discrete Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Compression Or Coding Systems Of Tv Signals (AREA)

Abstract

Les modes de réalisation de la présente demande divulguent un procédé de transformation, un codeur, un décodeur et un support de stockage. Ledit procédé comprend les étapes consistant à : déterminer des paramètres de mode de prédiction du bloc actuel ; lorsque les paramètres de mode de prédiction indiquent que le bloc actuel utilise une intra-prédiction basée sur une matrice (MIP) pour déterminer une valeur de prédiction intra-trame, déterminer des paramètres de MIP ; selon les paramètres de MIP, déterminer une valeur de prédiction intra-trame du bloc actuel et calculer une valeur de différence de prédiction entre ladite valeur de prédiction intra-trame et la valeur de prédiction intra-trame du bloc actuel ; effectuer une première transformée sur la valeur de différence de prédiction pour obtenir une première matrice de coefficients ; lorsque le bloc actuel utilise une transformée non séparable basse fréquence (LFNST), déterminer, selon les paramètres de MIP, un ordre de balayage de coefficient de LFNST utilisé par le bloc actuel ; construire une matrice de coefficients d'entrée de LFNST selon l'ordre de balayage de coefficient de LFNST et à l'aide de la première matrice de coefficients ; et effectuer un traitement de LFNST sur la matrice de coefficients d'entrée pour obtenir une matrice de coefficients de transformée du bloc actuel ; la première transformée est une transformée différente de LFNST et l'ordre de balayage de coefficient de LFNST comprend un ordre de balayage horizontal et un ordre de balayage vertical.
PCT/CN2019/130127 2019-12-30 2019-12-30 Procédé de transformation, codeur, décodeur et support de stockage WO2021134303A1 (fr)

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PCT/CN2019/130127 WO2021134303A1 (fr) 2019-12-30 2019-12-30 Procédé de transformation, codeur, décodeur et support de stockage
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